figure



NAL FOR PRINTED CIRCUIT BOARD June 9, 1964 R. c. SWENGEL SPRING CLIPTERMI Original Filed Feb. 11, 1 957 INVENTOR. ROBERT C. SwENGEL UnitedStates Patent 25,591 SPRING CLIP TERMINAL FOR PRINTED CIRCUIT BOARDRobert C. Swengel, Hellam, Pa., assignor to AMP Incorporated,Harrisburg, Pa.

Original No. 3,079,578, dated Feb. 26, 1963, Ser. No. 46,854, June 22,1960, which is a division of Ser. No. 639,461, Feb. 11, 1957, now PatentNo. 2,980,878, dated Apr. 18, 1961. Application for reissue Apr. 9,1963, Ser. No. 272,825

7 Claims. (Cl. 339-17) Matter enclosed in heavy brackets I: appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

This invention relates to printed circuit connections and moreparticularly to an improved printed circuit board or panel and terminalclips cooperable therewith for making connections between the electricalnetwork defined by the printed circuit board and electrical circuitryexternal to the printed circuit board. This application is a division ofmy copending application, Serial No. 639,461, filed February 11, 1957,now Patent No. 2,980,878, issued April 18, 1961.

As used herein, the term printed circuit board includes a supportingbase or body of any suitable insulating material on which the electricalWiring of an electronic circuit is reproduced by any suitable processsuch as chemical deposition, die stamping, painting, etc. The circuitdesign may encompass both sides of the panel and may be printed with orwithout other circuit parameters such as resistors, capacitors, etc.,the wiring usually taking the form of extremely thin and narrow stripsor ribbons of electrically conductive material such as copper, silver,or tin, or a combination thereof.

It is therefore an object of the present invention to provide electricalconnections with printed circuit boards which are simple in constructionand in installation and inexpensive to produce;

Another object is to provide a printed circuit connection for externalwiring which :may readily be disconnected for disassociating theprinting circuit unit from the remainder of the system;

Another object of the present invention is to provide a printed circuitpanel connection wherein an external lead wire is directly coupled tothe printed circuit conductive ribbons through a single solderlessterminal part;

Still another object is to provide in a friction fit connection forprinted circuit panels, connector parts which are self-cleansing,require low connective forces, but result in high contact pressures overthe contact areas without damage to the conductive ribbons of theprinted circuit panel;

Still another object is to provide in a frictional fit connection forprinted circuit panels, a terminal clip sufiiciently resilient to acceptwide variations in thickness of the insulation body and to overcomeplastic creep of the insulation under load;

A still furtherobject is to provide in a frictional fit connection forprinted circuit panels a terminal clip which promotes the circulation ofair for ventilation purposes and avoids entrapment of moisture or otherforeign matter within the connector parts;

A still further object is to provide in a friction fit connection forprinted circuit panels a terminal clip which is mechanically stableunder vibration or externally imposed stresses on the lead-in wires.

In general these and other objectives are attained in accordance withthe present invention by providing in a printed circuit panel aplurality of slots which extend inwardly from one or more of the sideedges of the panel, the number of slots corresponding to the number ofex- Reissued June 9, 1964 ternal connections desired. Incorporatedwithin the circuit design printed on the panel are a number ofconductive ribbons leading from the input and output junctions of thecircuitry involved, which ribbons extend to the panel side edges alongand adjacent appropriate slots. These slots are adapted to receive asheet metal terminal which includes a coupling portion adapted forsolderless connection to electrical circuitry, such as a lead-in wireexternal of the panel, and a clip portion which comprises a base andresilient spring elements extending from the base, for example, a pairof lateral arms extending from opposite sides of and turned back uponthe base. In connection the clip base is received within an appropriatepanel slot with the end edges of the spring arms gripping the panelresiliently therebetween with at least one of the end edges bearing uponan adjacent lead ribbon.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there are shown and described illustrative embodiments of theinvention; it is to be understood however that these embodiments are notintended to be exhaustive nor limiting on the scope of the invention butare given for purposes of illustration in order that others skilled inthe art may fully understand the invention and the principles thereofand the manner of applying it in practical use so that they may modifyit in various forms each as may be best suited to the conditions of aparticular use.

In the drawings:

FIGURE 1 is a fragmentary view in perspective of a printed circuit boardhaving connections made in accordance with the present invention;

FIGURE 2 is an enlarged view in perspective of the form of terminalprior to attachment of a lead wire for making connections laterally ofthe printed circuit board as shown in FIGURE 1; and

FIGURE 3 is an enlarged fragmentary side view of the terminal of FIGURE2.

Referring now to FIGURE 1, a printed circuit board panel or body 2 ofsuitable insulation material has reproduced thereon a circuit pattern ordesign including a plurality of thin narrow strips or ribbons 4 ofconductive material which represent the intercomponent wiring of anelectronic assembly. The ends 6 of some of strips 4 terminate atapertures 8 into which the leads of components, not shown, such asresistors, coils, tubes, etc., are inserted and then soldered, all as isconventional in the art. The printed circuit design may be composed ofstrips 4 on either, or as is the usual case, on both sides of panel 2,the connection of my invention being applicable in either case.

The segments or strip ends 10 which constitute the input and outputleads of the circuit defined by strips 4 are brought, in accordance withthe present invention, to any side edge 12 of panel 2, and, for reasonsto become apparent, preferably are widened to several times theapproximate 0.025 inch strip width usually sufficient for strips 4.Extending inwardly of side edge 12 adjacent and along strip ends 10respectively are a plurality of slots 14, each being adapted to receivein electrical connection with the associated strip end 10 a terminal 16attached to the end of an external lead 18. By bringing strip ends 10 tovarious edges of the board, it will be apparent that like connectionsmay be made on any side of panel 2 although, as is shown in FIGURE 1,all connections are conveniently made in practice along one side edge12. The connection afforded by terminal 16 thus serves to coupleexternal lead wire 18 to the desired input or output strip end 10, anydesired number of such connections being provided, corresponding, forexample, to the num- 6 her of input or output leads required to completeincorporation of the circuit of the printed circuit board within theelectrical equipment involved.

Terminal 16, of suitably resilient sheet metal such as No. 4.hard brass,includes a clip portion 20, FIGURE 2 for contacting strip ends 10, and acoupling portion 22 integrally connected to clip '20 by transitionsection 24, coupling portion 22 being adapted to aflix the terminalelectrically and mechanically to lead wire 18 as generally indicated inFIGURE 1. Clip 20 comprises a generally rectangular base 26 adapted tohe slipped within a slot 14 at right angles to panel 2, and opposedspring arms 28 and 29 extending from opposite sides of and turned backupon base 26 to terminate in longitudinally directed linear end edges 30and 31 spaced to engage resiliently the upper .and lower faces of panel2. More particularly, arms 28 and 29 are turned back upon base 26 aboutradii of curvature as large as possible to avoid concentration ofstresses during flexure, and extend linearly thereafter outwardly frombase 26 to form therewith an open-ended channel for receiving an edgeportion of panel 2 as defined by one side of a slot 14. Edges 30 and 31,however, are spaced less than any anticipated thickness of panel 2 sothat on assembling the connection these edges forcibly bear on theopposed surfaces of the board and on the conductive strips with whichthe slot is associated.

In general coupling portion 22 may take a variety of forms but issolderless in nature, that is, a ferrule-forming part adapted to be coldcrimped onto the end of lead wire 18 by solderless techniques Well knownin the art. Such a ferrule typically includes a U-shaped portion havingfirst upstanding ears 32 adapted for turning inwardly and downwardlyupon the exposed metallic core of lead 18 and a second pair of ears 34which are formed about the insulation, if any, of the lead in thecrimping process. Alternatively, coupling portion 22 may be omittedwhere the function to be served is to couple opposed strips on the upperand lower surfaces of the board. Transition section 24 serves to reducethe wider clip portion to the width of coupling portion 22 and isflanged at edges 3 to lend rigidity to the construction.

It will be apparent that terminal 16 may be formed from sheet metal byconventional blanking and shaping techniques well known in "the art,conveniently in strip form, that is a string of terminals wherein eachterminal is joined to others in ladder form, not shown. When thus formedthe terminals may be wound in reels for application to leads 18 byautomatic or semi-automatic crimping machines.

With coupling portion 22 crimped onto the end of lead wire 18, insertionof clip base 20 within a slot 14 and introduction of an edge portion ofthe board within the channel defined by the clip cause resilient springarms 28 and 29 to be wedged open and end edges 30 and 31 to be broughtinto forceful engagement with strip ends thereby providing the desiredsolderless connection between lead wire 18 and printed circuit strips 4.To facilitate application of base 20 to the appropriate slot 14 theforward corner 38 of arm 28 is chamfered or beveled so as to curve awayfrom the insertion end of the clip thus to produce initially a smoothcaruming action for distending the spring arms. In addition the width ofslot 14 will, of course, be wider than the thickness of base 20 toprovide a target area of suitable scope for facile indexing of the clipbase.

Electric continuity between clip 20 and a strip 4 will be seen to be aline contact afforded by end edges 30 and 31 hearing on strip ends 10.To avoid damaging the relatively delicate printed circuits strips,typically of the order of .001 inch in thickness, inside corner 40 ofend edge 30 is rounded as best shown in the enlarged cross sectionalview of FIGURE 3.

In making the connection, as the clip is slipped into position, therelatively harder metal of the clip is caused at end edges 30 and 31forcefully to bear on a very limited area of the softer metal of theprinted circuit strips, commonly a base of copper overlaid with tin.Because of the small area of contact even relatively small distensionsof the clip spring arms result in relatively high contact pressures thatdeform and slightly groove the metal of the strips as end edges 30 and31 progress therealong. Rounded corner 4-0, however, effectivelyincreases the bearing surface sufficiently to prevent shearing of theconductive strips. Advantageously, the burnishing and grooving actionremoves any foreign material while exposing fresh metal at the contactsurfaces.

As shown in the drawings, terminal 15] 16 is of a flag-type constructionwherein the base 26 and one of the spring arms 29 of the clip portionare formed in a double layer of sheet metal, the two layers beingintegrally joined along the end edge 31 of arm 29. Transition section orshank portion 24 is a lateral continuation of the bottom layer of thedouble layer base 26 with the longitudinal axis of the ferrule-formingor coupling portion [52E 22 laterally extending centrally of the clipportion. Advantageously, on insertion of the clip fully within a slot14, no portion of the terminal extends beyond the board edge in theplane of the board. In addition this embodiment is suitable for makingconnections centrally of the board, requiring only that the board beapertured, as at 42 in FIGURE 1, to permit passage of the clip portionendwise into the board. Aperture 42 includes a slot extension 44 forreception of base 26, strip end 46 being disposed adjacent the slot forcontact by the clip arms to effect a connection similar to that as hasbeen described.

The embodiment illustrated by the foregoing description achieves thestated objectives, primarily being the provision of a solderlessfrictional-fit connection for printed circuit applications which isversatile, of high electrical and mechanical quality, simple in assemblyand inexpensive in construction. It will be apparent that the basicprinciples disclosed admit of many modifications within the scope of theinvention which will occur to those skilled in the art. By way ofspecific example dimensionally, however, good results can be obtained ina connection formed in accordance with the embodiment wherein panel 2 is006210.005 in thickness, slots 14 being spaced along the panel edge of0.156 centers and each having a width of 0.020 and a length of 0.210,and strips 4 (tin-clad copper) being 0.001 in thickness with strip ends19 being 0.100 in width, all dimensions being in inches. Terminal 16 maybe formed of No. 4 hard tin-plated brass 0.010 in thickness, clipportion 20 being 0.200 in length and 0.153 in width and having springarms turned about a 0.020 radius to extend at approximately a 30 angleto base 26 and to a height of 0.080 thereabove. The relative spacing ofedges 30 and 31 approximates 0.050, the inside corners being brokenabout a radius of approximately 0.003. It will be observed that stripends 10 are sufiiciently wide, relative to the overhand, of spring arms28 and 29 over the panel face, to accommodate substantial variation inthe location of the contact line.

I claim:

1. An integral sheet metal terminal comprising a coupling portion forconnecting the terminal to a conductor wire, and a spring clip portionincluding a base and a pair of lateral arms extending from oppositesides of and turned back upon said base, the end edges of said armsbeing spaced from each other, at least one of said end edges beingsmoothly rounded, said coupling portion extending laterally from one ofsaid opposite sides and integrally joined to said clip portion at theend edge of the arm extending from the other of said opposite sides.

2. An electrical connection comprising a printed circuit panel having aslot adjacent a conductive ribbon, an integral sheet metal terminalcomprising a coupling portion for connecting the terminal to electricalcircuitry external of the circuit panel, and a spring clip portionincluding a base and a pair of lateral arms extending from oppositesides of and turned back upon said base, the thickness of the sheetmetal forming said clip being less than the width of the slot, the endedges of said arms having a relaxed relative spacing less than thethickness of the panel so that with the clip base arranged in the slotsaid arms are [distened] distended and grip the panel with springpressure, one of said edges bearing upon the adjacent conductive ribbon,said coupling portion extending laterally from one of said oppositesides and integrally joined to said clip portion at the end edge of thearm extending from the other of said opposite sides.

3. An electrical terminal for frictionally engaging a flat plate-likecontact member comprising a one-piece sheet metal stamping of a couplingportion including a trough having ears upstanding from the sides thereoffor crimping onto a conductor wire, a spring clip portion including abase and a pair of lateral spring arms extending from opposite sides ofand turned back over said base for slidably engaging a contact memberinserted in and along the axis of the clip portion in a directioncoaxial with said sides, and a shank portion connecting said couplingand clip portions, said shank portion extending irom said clip portionlaterally of said axis.

4. A sheet metal terminal as set forth in claim 3 Wherein said shankportion laterally projects from one of said opposite sides andintegrally joins with the spring arm on the other of said oppositesides.

5. A sheet metal terminal as set forth in claim 3 wherein thelongitudinal axis of said trough is perpendicular to the axis of theclip portion.

6. An electrical terminal for frictionally engaging a flat plate-likecontact member comprising a one-piece sheet metal stamping including atrough having ears upstanding from the sides thereof for crimping onto aconductor wire, and a spring clip including a base and a pair of lateralspring arms extending from opposite sides of and turned back over onesurface of said base for slidably engaging a contact member inserted inand along the axis of the clip in a direction coaxial with said sides,

and means having opposite ends respectively joined with said trough andclip with said trough being disposed substantially centrally relative tosaid clip, sid means adjacent one end extending laterally of said axisand at the other end being disposed adjacent the other surface of thebase to open said clip at either end for reception of said contactmember.

7. An electrical terminal for frictionally engaging a flat plate-likecontact member comprising a one-piece sheet metal stamping including atrough having ears upstanding from the sides thereof for crimping onto aconductor wire, a spring clip including a base and a pair of lateralspring arms extending from opposite sides of and turned back over onesurface of said base to define a channel for slidably engaging a contactmember inserted in and along the axis of the clip in a direction coaxialwith said channel, and means having opposite ends respectively joinedwith said trough and clip with said trough being disposed substantiallycentrally relative to said clip to confine the length of the terminal tosubstantially the length 0 said channel, said means adjacent one endextending laterally of said axis and at the other end being disposedadjacent the other surface of the base to open said clip at either endfor reception of said contact member and to dispose said conductor wirewhen crimped onto said trough transverse of said axis.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS 1,827,533 Martin Oct. 13, 1931 1,841,736 JonesIan. 19, 1932 2,526,937 Cripe Oct. 24, 1950 2,945,206 Hammell July 12,1960 OTHER REFERENCES AMP, Electronic Design, Nov. 15, 1956, page 17.

